There is a demand for new methods of contraception than can provide protection against unintended pregnancies as well as reduce risk of venous thromboembolism (VTE), particularly for obese women. The mission of the CCTN is to develop protocols and conduct clinical trials that assist in providing effective and safe contraception in women. The National Institutes of Health (NIH), Eunice Kennedy Shriver National Institute of Child Health and Human Development (NICHD), is the lead Federal agency for the conduct of basic, clinical research to develop new contraceptives and to evaluate existing methods of contraception and reproductive health. The Center for Population Research (CPR), within NICHD, was established in 1968 by the Secretary of Health Education and Welfare, with the important goal of developing new contraceptives through the use of contracts and grants. Within CPR, the Contraception and Reproductive Health Branch (CRHB) has long supported several preclinical contraceptive testing facilities as well as facilities for synthetic chemical and synthetic peptide formulation. To measure hormones and other biological assays as defined by the protocol, serving as laboratory in order to evaluate the contraceptive effectiveness, pharmacokinetics, bleeding patterns, side effects and safety of novel products for obese female contraception. III. OBJECTIVES To obtain valid and reliable assay data to determine the contraceptive effectiveness, pharmacokinetics, bleeding patterns, side effects and safety of novel products that can provide safe and effective contraception for women. To further expand their contraceptive development capabilities, in 1996 CRHB established the NICHD Contraceptive Clinical Trials Network (CCTN). The current CCTN has conducted Phase I, II, and III clinical trials of contraceptive methods .With the recompetition of the CCTN, clinical sites will perform Phase I, II, III, and Phase IV clinical trials of a wide variety of new or existing female contraceptive methods.